1. Field of the Invention
The present invention relates to a light emitting diode mounting structure, and more particularly to a light emitting diode mounting structure that is suitable for application to a vehicular lamp.
2. Description of the Related Art
The leads of a light emitting diode used in such applications as vehicular lamps are soldered to a printed circuit board that is provided on the lamp, according to, for example, the disclosure of the Japanese laid-open patent application publication H10-188614. 
In a structure whereby a light emitting diode is soldered to a printed circuit board, however, if the light axis of the light emitting diode is shifted because of such effects as deformation of the leads, there is possibility that the effective rate of usage of the light from the light emitting diode drops. For this reason, in order to achieve the required brightness, it is necessary to use a large number of light emitting diodes, this being a disadvantage from the standpoint of cost.
Additionally, because each of the leads of the light emitting diode is soldered to the printed circuit board individually, the process of mounting the light emitting diode to the board is troublesome, and manufacturing efficiency is poor. When replacing a light emitting diode, the process of removing leads from their positions on the printed circuit board and resoldering leads is complex.
Accordingly, in view of the related art, it is an object of the present invention to provide a light emitting diode mounting structure with superior light usage and work efficiency.
To achieve the above-noted object, the first aspect of a structure according to the present invention has a light emitting diode having a lead, and a metal plate fixed and connected to a wire on an upper housing. The lead engages the metal plate so as to make an electrical connection therewith, and is support thereby. The surface part of the metal plate has a surface area that is capable of reflecting light from the light emitting diode.
In the above-noted configuration, a surface part having a surface area capable of reflecting the light of the light emitting diode is formed on the metal plate. For this reason, the light usage efficiency of the light emitting diode is improved, the result being that a smaller number of light emitting diodes can be used to achieve the required brightness, thereby simplifying the structure and reducing the cost.
The above-noted light emitting diode can also have four leads, these leads being engaged with two metal plates that are disposed in proximity.
In the above-noted configuration, because there are four leads, the light emitting diode does not tend to bend over and does not tend to change its direction after mounting. Additionally, because two metal plates are used to mount one light emitting diode, the size of one metal plate can be made small, thereby facilitating manufacture of the metal plates. Additionally, because the two metal plates are in mutual proximity, there is little affect on the rate of usage of the light.
The lead can be formed of a metal that has a thermal conductivity that is equivalent to or greater than that of copper.
In the above-noted configuration, because the lead is formed of a metal having a thermal conductivity that is equivalent to or greater than of copper, heat that is generated by the light emitting diode is reliably transmitted via the lead to the metal plate, where it is radiated from the surface part thereof. There is thus an improvement in the heat radiation of the light emitting diode.
The wire can be formed by an insulation covering and a center conductor disposed within the insulation cover, and the metal plate can be formed by a foot part that faces the housing, and a cutting groove part that is formed in the end of the foot part. When the wire is inserted into the cut groove part, the cutting groove cuts the insulation covering of the wire, and eats thereinto, the effect being that the metal plate comes into a conductive connection with the center conductor, and holds the wire in place.
In the above-noted configuration, a cutting groove formed in the foot part of the metal plate cuts the insulation covering of the wire and bites into the inside thereof so that an electrical connection is made to the center conductor, the biting force between the cutting groove and the wire also serving to hold the light emitting diode in one operation to the wire. For this reason, it is not necessary to perform a soldering operation to mount the light emitting diode in place, and it easy to replace the light emitting diode. Additionally, because it is possible to use the surface part of the metal plate as a surface for an operator to press with a finger, the operation of pressing the metal plate to press the wire into the cutting groove is facilitated.
The surface part of the metal plate can also be a surface that is colored with a metallic coloring.
In the above-noted configuration, because a metallic coloring is imparted to the surface part of the metal plate, good reflection of light is achieved, thereby further improving the usage of light.
The construction of the second embodiment of the present invention has two light emitting diodes each having a lead, and two metal plates each being connected to a wire on an upper housing. The leads engage with the metal plates so as to make an electrically conductive connection thereto. Each metal plate has a hole for the purpose of connecting a jumper wire between the metal plates.
In the above-noted configuration, even if the wire between neighboring metal plates is broken, because of the connection made by the jumper wire between the metal plates, it is possible to maintain the electrical connection between the metal plates.
The mounting structure according to the third embodiment has a light emitting diode having a lead, a non-metallic holder that engages with a housing, and a metal connecting member that is mounted to the holder. The connecting member has an integrally formed foot part and clip part. The lead is resiliently grabbed and supported by the clip part. The foot part has at its end a cutting groove that accepts the wire on the housing. The wire is formed by an insulation covering and a center conductor disposed therewithin. When the wire is inserted into the cutting groove, the cutting groove cuts the insulation covering of the wire and bites into the inside thereof, thereby making an electrically conducting connection between the connecting member and the center conductor, and also holding the wire in place.
In the above-noted configuration, because of the connecting member that is mounted to a holder engaged with the housing, the connecting member is securely held to the housing. Because the light emitting diode is resiliently grabbed and supported by the clip part of the connecting member, it is held in place with respect to the housing. As a result, the light emitting diode is held securely to the housing, thereby resulting in a stable light axis. Because the light axis of the light emitting diode is stabilized in this manner, there is an improvement in the usage of the light thereof. For this reason, the number of light emitting diodes required to achieve the desired brightness is reduced, thereby simplifying the structure and reducing the cost. Additionally, because the cutting groove formed in the foot part of the connecting member bites into the inside of the wire insulation covering, the biting force between the cutting groove and the wire holds the wire in place with a single operation. Additionally, it is possible to hold the light emitting diode in place by inserting the wire into the clip part, thereby eliminating the need of a soldering operation to hold the lead in place, thereby simplifying the mounting task. This not only improves manufacturing efficiency and enables automation thereof, but also facilitates replacement of the light emitting diode.
The light emitting diode can have four leads, the holder can have two neighboring connecting members mounted to it, and each connecting member can have two clip parts. It is also possible for each of the connecting members to have two cutting grooves. The four leads are each grabbed and supported by the clip parts.
In the above-noted configuration, because a single light emitting diode is held in place by two connecting members, the size of each connecting member is reduced, thereby facilitating the manufacture of the connecting members.
The clip parts can be exposed from the holder, in which case because of the exposure of the clip parts from the holder heat generated by the light emitting diode is radiated from the clip parts, thereby improving the heat radiation performance of the light emitting diode.
The leads can be formed of a metal that has a thermal conductivity equivalent to or greater than that of copper.
In the above-noted configuration, because the leads are made of a metal that has a thermal conductivity equivalent to or greater than that of copper, heat generated by the light emitting diode is reliably transmitted to the metal plates via the leads, and is radiated from the clip parts. There is therefore a further improvement in the heat radiation performance of the light emitting diode.